The invention pertains to conveyor motion sensing apparatus utilizing a traction wheel engaging the moving conveyor member to be sensed.
In the material handling art wherein bulk materials are being conveyed by a plurality of conveyors, one conveyor supplying another, it is most important that the designed operating characteristics of the conveyors be maintained during operation in order to prevent clogging and overloading. For instance, in a typical installation wherein a screw or belt conveyor is supplying bulk material to the lower end of a bucket conveyor which is elevating material, malfunctioning of the bucket conveyor will quickly cause clogging if the rate of movement of the bucket conveyor is not sufficient to accomodate the discharge from the supplying screw or belt conveyor. In many bulk material conveying systems a plurality of various types of endless conveyors are often interrelated, and it is necessary that the designed operating specifications be maintained in order to prevent a chain of malfunctions due to one of the conveyors in the system slowing down, or stopping completely, due to overloading, belt slippage, drive motor overheating or burn out, drive train failure, broken parts, or the like.
In order to prevent overloading in conveyor systems it is common practice to use motion sensing devices with the conveyor which continuously sense the rate of conveyor movement, and in the event that conveyor movement varies from a predetermined rate an alarm is energized, or the entire conveyor system may be deactivated, depending on the control system utilized. Such safety devices usually include sensing means of the rotational type capable of discerning small deviations in the rate of velocity of conveyor chain or belt movement, or the rate of rotation of the conveyor drive or idle pulleys.
Rotational motion control sensors for endless conveyors of the bucket or belt type are often mechanically connected to the conveyor idler or tail pulley for rotation thereby as the pulley is rotated by conveyor movement. However, with certain configurations of conveyors it is possible for the rate of rotation of the tail pulley to not accurately represent the condition of the conveyor rate of movement, and several state requirements now insist that conveyor safety devices directly indicate the rate of conveyor movement by directly engaging the conveyor component. However, as conveyors are often custom designed, and are manufactured by a great number of sources, and as the dimensions of conveyor systems are not standardized, considerable difficulty is often encountered in mounting the sensing apparatus for direct engagement with the moving conveyor components. Because of the significant differences in dimensions and configurations of conveyors considerable difficulty has been encountered in endeavoring to provide sensing apparatus which is substantially universal in installation to accommodate the many conveyor installations already in existence.
Sensing devices directly engaging the moving conveyor components may utilize a traction wheel frictionally engaging a movable conveyor component, and it is necessary that the traction wheel be accurately positioned with respect to the engaged conveyor components to insure consistent driving of the wheel. The wheel is associated with a motion sensor wherein the rate of wheel rotation is transferred to the sensor. In an elevating conveyor of the bucket type the traction wheel is normally mounted on the conveyor frame adjacent the backside of the conveyor "up" leg, and the traction wheel may engage the conveyor chain, or the back of the conveyor belt or web to which buckets are attached. As the distance between the conveyor frame or housing to which the sensing apparatus must be attached, and the conveyor components within the housing, widely differ between various conveyor manufacturers and models it is necessary that the sensing apparatus be capable of an extended range of adjustment between the traction wheel shaft and the shaft supporting structure, and motion sensing apparatus of the traction wheel type previous available has not proven satisfactory to meet the requirements of the present market.